Over recent years, communication terminals typified by mobile telephones have arrived at still picture filming functions and moving picture communication functions such as in TV telephones by connecting to or incorporating camera apparatus.
Generally, moving picture compression schemes used for bidirectional moving picture communication such as by TV telephones fall under simple profile level 1 by MPEG-4, which is an international standard scheme, and the resolution for corresponding picture data is QCIF (176 pixels*144 lines).
In addition, in terms of the resolution of display devices such as liquid crystal panels mounted in communication terminals typified by mobile telephones, the number of horizontal pixels and the number of vertical lines are both around 100 to approximately 200. Therefore, when moving picture filmed with a camera apparatus is displayed on a display device, QCIF is a sufficient resolution level for the moving picture data.
As thus described, in either case of when a moving picture is compressed by MPEG-4 or when a camera picture is displayed, QCIF is still an adequate resolution level for moving picture data that camera apparatus mounted in communication terminals requires.
Meanwhile, pictures filmed as still pictures can be transferred to personal computers and such and viewed on a display device of higher resolution. So, as with communication terminals typified by mobile telephones too, with respect to still picture filming functions, still picture data should ideally have higher resolution than QCIF, such as VGA (640 pixels*480 lines).
As explained above, although the resolution required for camera apparatus for use with communication terminals is approximately QCIF for moving pictures, higher resolution is yet required as for still pictures. However, if an imaging device of high resolution is used in quality of a camera apparatus in accordance with demand for a resolution for still pictures, and if moving picture data is being used and meanwhile picture data of similarly high resolution is used, the transfer speed of camera output signals increases, which is a factor that leads to increased power consumption. At the same time, on the moving picture data receiver side, an increase in memory capacity occurs correspondingly with high resolution, and as a result, power consumption, cost, and the component area will increase.
As a solution to this problem, there is a technique for compressing and transferring data that is output from camera apparatus recited in Japanese Unexamined Patent Application Publication No.HEI6-315105.
This prior art (hereinafter “the first prior art”) employs a configuration comprising an imaging section which changes signals of the filmed object into signals for low-resolution moving pictures and signals for high-resolution still pictures, a compression section which performs moving picture compression and still picture compression, a control section, and a transmission section. The control section instructs the imaging section and the compression section as to the operation mode for moving pictures and for still pictures. The imaging section, following the instruction from the control section, outputs picture signals. The compression section, following the instruction from the control section, performs compression adequate for moving pictures and still pictures respectively and outputs the compressed data to the transmission section. By thus compressing all the data output from the camera apparatus, the transmission speed for camera output signals can be moderated without an increase in memory capacity on the compression data receiver side.
Another technique is disclosed in, for instance, Japanese Unexamined Patent Application Publication No.11-112932, wherein data output from camera apparatus can be chosen between live picture data from an imaging section and compression data such as JPEG.
This prior art (hereinafter “the second prior art”) employs a configuration comprising an imaging section, a memory which stores picture data output from the imaging section, a signal processing section which performs color conversion and ã conversion and such, a compression circuit which performs JPEG compression and such, and an external recorder medium. A pathway is provided to directly transfer data from the memory that stores picture data to the external recorder medium; this pathway is used when live picture data from the imaging section is recorded into the external memory medium. In case compression data is recorded into the external recorder medium, the data is supplied from the memory storing picture data to the signal processing circuit, and from the signal processing circuit through the compression circuit, the compression data is recorded into the external recorder medium. By this means, both live picture data and compression data such as JPEG can be obtained from the camera apparatus.
However, as with the apparatus according to the first prior art, both still pictures and moving pictures are compressed. So, when the moving pictures too are compression data to be displayed on communication terminals, a separate circuit is needed to extend the compression data. This results in an increase in the circuit scale and power consumption at the communication terminals.
In addition, with the apparatus according to the second prior art, a number of pathways for recording data into the external recorder medium need to be provided, which results in an increase in the circuit scale of the camera apparatus. In addition, data recording control in respect to the external recorder medium requires several schemes, which makes the processing complex.